Only one o2 sensor. Anyway, lean burn is a completely electrical thing. You'll just have to see, it's a touchy system, at best.
Im not liking the sound of that statement. You mean that lean burn is so touchy that It may not work because the car is old? If it is just electrical, what would need to be replaced to make it work again?
Since this past friday when Ben (SVO) helped swap in an hf transmission, I have gone from a base of 37mpg to 44mpg. That is not trying, whereas before I got 43-44mpg driving less aggressive, and EOCing, I am hoping for around 50mpg with those same practices. We shall see!